1. Field of the Invention
The present invention relates to a document imager that is connected with a projector and captures an image of an original document mounted thereon to supply an image signal, a document stillness detection method, and a computer program product.
2. Description of the Related Art
There is conventionally a system having a structure in which a camera with a document bed plate called a document camera is connected with a personal computer and a projector device and an image of a document mounted on the document bed plate is captured as required to be projected and displayed as it is.
In this type of document camera, there has been conventionally considered a technology by which an image of a document mounted on the document bed plate is not simply output in a captured state, but an image of the document bed plate is not output until a document is placed at a correct position and stands still when placing the document on the document bed plate or an image immediately before any change in the document on the document bed plate is kept being output in order to prevent a complicated image from being projected at the time of presentation.
For example, Jpn. Pat. Appln. KOKAI Publication No. 2005-123752 (Patent Document 1) proposes a technology of detecting stillness of an original document on a document bed plate and determining that the original document is placed when an image has a fixed number or more of linear components (the number of edges included in the image).
Jpn. Pat. Appln. KOKAI Publication No. 2000-308045 (Patent Document 2) proposes a technology of separating an image of an original document from that of a hand since capturing images of both the original document and the hand in a close field is inconvenient although it is not a technology concerning the document camera itself.
The technology disclosed in Patent Document 1 cannot determine that an original document is placed since a linear part in an image becomes discontinuous on a stage where a user's hand covers an end of the original document and an amount of the linear part is reduced.
The technology disclosed in Patent Document 2 cannot be applied to a document camera having a structure in which an original document is mounted on a document bed plate.